1. Field of the Invention
The present invention relates to a Venetian blind slat positioning device, and particularly, to a Venetian blind slat positioning device that is easily rotatable.
2. Description of Related Art
With reference to FIGS. 8 and 9, the conventional slat positioning device comprises a base (60) and a positioning drum (40) rotatably mounted in the base (60). The positioning drum (40) comprises two ridges (45), two tapered grooves (42), two recesses (43) and an axial passage (41). The two ridges (45) are integrally formed on the top side of the positioning drum (40). The two tapered grooves (42) each extends from one of the end of the corresponding ridge (45). Each recess (43) is formed at the junction of the ridge (45) and tapered groove (42). The axial passage (41) extends along the central axis of the positioning drum (40). A control rod (61) is inserted into the axial passage (41), and the positioning drum (40) is rotatably mounted in the base (60). Each of two holding rods (51) has a holding protuberance (511) near the end of the rod (51). Each holding rod (51) is capable of being inserted into one of the ridges (45) through the tapered groove (42) to allow the protuberance (511) to be received in the recess (43). One cord is (52) firmly attached to each holding rod (51) and extends through one of the recesses (43) to hold the Venetian blind slats. When operated, the positioning drum (40) can be rotated clockwise or counterclockwise to allow the cord (52) to move up or down, such that the angular position of the Venetian blind slats is controlled.
However, a problem exists in this conventional slat positioning device. The axial passage (41) through the positioning drum (40) is flush with the ends of the positioning drum (40), so that the control rod (61) is actually in contact with the base (60). To ensure that the positioning drum (40) does not slip on the control rod (61), both the positioning drum (40) and the control rod (61) have corresponding facets. Because of the facets on the control rod (61), the control rod (61) does not rotate smoothly on the base (60).
With reference to FIG. 10, another conventional positioning drum (70) is provided. The positioning drum (70) can be used with a Venetian blind using connecting tapes (80) to hold the slats. The positioning drum (70) comprises two tapered recesses (72) and two lateral posts (74). Two tapes (80) used to hold the Venetian blind slats are respectively attached to each post (74) and extend through the corresponding recesses (72). However, the axial passage (71) of this conventional drum (70) is also flush with the ends of the positioning drum (70), such that the rotation of the positioning drum (70) is also restricted by the base (not shown) and influenced by the facets on the control rod (not shown) that passes through the axial passage (71).
In view of the foregoing, a Venetian blind slat positioning device that is easily rotatable is desired.